As always the Drupal Association puts videe-recording of most sessions on DrupalCon Youtube.
That is also true for the now ongoing DrupalCon New Orleans 2016.
An excellent option for learning and understanding Drupal. (and following the event!)
Recored video-sessions on YouTube
Thanks so much!
I liked this one about theming because it explains the theming-system in a clear way:
This one: GraphQL meets Drupal. Very promisfull for headless-sites and api-serving sites in general.
And at last the Driesnote. I must say I liked it good times. Well prepared presentaion about the foresable future with drupal 8 this and next year. Good high-level overview on the Drupal Ecosystem and status n general"